Outboard motor driven hydroplaning boat



Oct. 20, 1959 Oct. 20,1959 E. c. KIEKHAEFER 2,909,1 0

OUTBOARD MOTOR DRIVEN HYDROPLANING BOAT Filed Se t. 22, 1958 2 Sheets-Sheet 2 INVENTOR. ELMEH C IQEKHAEFER United States Patent OUTBOARD MOTOR DgAVEN HYDROPLANING B T Elmer Carl Kiekhaefer, Cedar-burg, Wis.

Application September 22, 1958, Serial No. 762,328

7 Claims. (Cl. 1 14-66.5)

This invention relates to an outboard motor driven hydroplaning boat.

Hydroplaning boats of various types are commonly propelled by dirigible outboard motors. Frequently such craft are designed to have the propeller of the motor unit partially withdrawn from the water to operate under surface pitch conditions to hold the boat on its correct planing angle and thereby achieve a minimum of incident resistance.

Such boats are generally prone to sideslip or skidding when traveling at high speeds, especially when making a turn. For this reason vertical water reaction surfaces, such as fins or the like, are commonly provided and extend downwardly from the bottom of the boat. While such fins increase the stability of the boat, they also impose a drag which is detrimental to speed. Furthermore, with the propeller of the dirigible motor unit operating under surface pitch conditions, the boat responds sluggishly to steering control of the motor unit. It is generally an object of this invention, therefore, to eliminate the need for drag imposing underwater fins and otherwise provide for increased stability in the hydroplaning boat and to simultaneously provide for improved steering control of the boat.

According to this invention, a hydroplaning boat is provided with a hull having planing surfaces extending forwardly from generally amidship and cockpit or cab is disposed in the hull over the planing surfaces. The boat is driven by a dirigible outboard motor secured to the rear end of the boat, and at planing speeds the propeller thereof is adapted to operate under surface pitch conditions. The engine cowl of the motor extends upwardly above the boat hull. Vertical air reaction surfaces in the form of a wedge-shaped fin extends upwardly from the hull in alignment with the motor cowl and between the cockpit and the cowl and serve to direct air rearwardly to stabilize the boat at planing speeds. The cowl, being dirigible with the motor, provides air reaction surfaces for the flow of air directed rearwardly by the fin and thus serves as a rudder to effect steering control of the boat at planing speeds.

The drawings furnished herewith illustrate the best mode of carrying out the invention as presently contemplated and set forth hereinafter.

In the drawings:

Fig. 1 is a perspective view of the outboard motor driven hydroplaning boat of this invention shown in operation;

Fig. 2 is a front perspective view of the boat together with the outboard motor as viewed from the front and at an angle above the boat;

Fig. 3 is a diagrammatic sectional view looking forwardly and taken generally amidship and to the rear of the planing surfaces;

Fig. 4 is a partial top plan view showing the motor together with the wedge-shaped fin mounted above the hull of the boat and in dot-dash lines illustrates the mode of steering control for the boat;

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Fig. 5 is a partial side elevation of the outboard motor driven hydroplaning boat of this invention and shows an embodiment wherein a wedge-shaped fin is adapted to serve as a carburetor ram; and

Fig. 6 is a partial enlarged top plan view with parts broken away and sectioned showing details of the wedgeshaped fin equipped with a-carburetor ram.

Referring to the drawings, the hydroplaning boat 1 generally includes the hull 2 having outwardly projecting sponsons 3 extending forwardly from generally amidship to provide .the boat with added breadth and thereby increase its stability. The hull 2, as shown in Fig. 1, is provided with a generally streamlined deck 4 which is pointed at the bow and widens out toward amidship. The sponsons 3 are each provided with a lower planing surface 5 which are stepped beneath the bottom 6 of hull 2 amidship and extend forwardly and curve upwardly to merge with the bottom of the hull 2. The outermost sides of sponsons 3 are disposed angularly from planing surfaces 5 and serve as non-slip chines 7. The boat 1 further includes the vertical fins 8 which extend rearwardly from planing surfaces 5 at the inner edge thereof and serve generally to guide and entrap the natural flow of air beneath the hull gained by the momentum of the boat under way and thus provide greater lift for the hull. The depth of fins 8 at the forward end generally corresponds to the depth of the stepped planing surfaces 5 and as the fins 8 extend rearwardly they taper and merge with the hull bottom 6. It will be noted that the boat 1, shown in the drawing is devoid of fins or the like which project downwardly beneath the planing surfaces 5 and are commonly provided to enhance the stability of the craft. If desired, such fins may be provided, but they are known to impose a considerable drag on the boat detrimental to its speed.

A cockpit 9 for the operator is provided in the hull 2 of the boat and generally extends forward from amidship and above the planing surfaces 5. The boat further includes a transom 10 which is offset inwardly from the end of hull 2 and is adapted to support the dirigible outboard motor .11.

The motor 11 includes the usual bracket assembly 12 which is pivotally connected to motor housing 13 for turning movement of the motor on a vertical axis and is adapted for securement on transom 10 of the boat. The power head 14 including the internal-combustion engine 15 and the cowl enclosure 16 for the engine is-carried at the upper end of motor housing 13 and extends above.

the hull 2 of the boat. The cowl 16 is provided with a vertically extending opening 17 forwardly thereof for the admission of combustion air to the engine 15 and is tapered rearwardly to have a general teardrop configuration. The opposed sides 18 of cowl 16 provide reaction surfaces of substantial size to be utilized in a manner to be described hereinafter.

The gear case 19 including the downwardly extending skeg 20 is secured to the lower end of housing 13 and carries the propeller 21 rearwardly thereof. The propeller 21 is driven by the engine 15 through drive means, not shown, and is disposed beneath the anti-cavitation plate 22 spaced above gear case 19. I

As shown in Figs. 1-2, the boat 1 is provided with a dorsal wedge-shaped fin 23 which extends upwardly from the hull 2 and is disposed along the longitudinal centerline of the boat in alignment with the motor 11. Fin 23 extends generally from the rear of cockpit 9 amidship to a location spaced forwardly from power head 14 to provide an air slot 24 between the fin and power head. The leading edge 25 of fin 23 is generally pointed and slopes upwardly and rearwardly and terminates generally in line with the top of the power head 14. Pin 23 includes transversely spaced generally vertical side walls 3 26 which taper forwardly and upwardly to meet along the edge 25. The wedge-shaped fin 23 serves as an airfoil providing reaction surfaces for the. air through which it moves to stabilize the boat and generally directs the flow of air rearwardly.

When moving at high speed, as shown in Fig. 1, the

outboard motor driven boat 1 is principally supported 7 on the water over which it moves at three triangularly spaced locations. Forwardly, the transversely spaced planing surfaces are in contact with the water. The propeller 21 operating at surface pitch conditions provides a third and rearwardly disposed support.

As shown in Fig. 1, even the gear case 19 of the dirigible motor 11 is supported out of the Water at high speeds and, other than one blade of the surface pitch propeller 21, only the skeg 20 moves through the water. If only the direction of thrust of the dirigible propeller 21 together with turning of the small water reaction surfaces of the skeg 20 were relied upon to elfect turning movement of the boat, the response to steering control of the boat would be slow to the point of being extremely hazardous at high speed. According to this invention, turning movement of the boat is additionally efiected by the air reaction surfaces provided by the side walls 18 of power head 14. As the boat 1 moves at planing speeds, the flow of air directed rearwardly by the Wedge-shaped fin 23 impinges on one of the side walls 18 of the dirigible power head 14 in accordance with the direction of turning to provide a quickened and more positive response to steering control of the boat.

The dorsal wedge-shaped fin 27 of the embodiment shown in Fig. 5 is provided with a generally vertical leading edge 28 from which the sides 29 diverge rearwardly along straight lines. Each side 29 of fin 27 is provided with a plurality of vertically spaced forwardly opening air inlets or scoops 30 which project outwardly from the side and are adapted to receive a portion of the air directed rearwardly by the fin. Corresponding inlets 30 of the opposed sides 29 having merging passages 31 which direct the air rearwardly through a duct 32 Sup ported within the fin. T'he rearwardly disposed outlet 33 for each duct 32 is generally in alignment with the opening 17 provided forwardly of motor cowl 16. Air at high velocity moves from outlet 33 across the slot 24 into the cowl 16 through opening 17. The inlets 30 together with the air conduction means serve as a carburetor ram supplying the air for carburetion within the cowl 16. Through the carburetor ram some of the air velocity head is converted to a pressure head to eliminate negative pressures within the cowl and thereby increase the output of the engine 15.

The outboard motor driven hydroplaning boat generally depicted in the drawings and described hereinbefore is capable of speeds well in excess of 100 m.p.h. when driven by a particular stock outboard motor and is credited with returning the speed record to the United States for boats of this type for the first time in over twenty years. The instant invention is in part responsible for this achievement having provided the increased stability and more positive maneuverability required to safely operate boats of this type -at speeds heretofore never attained.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claimz' 1. In combination, a hydroplaning boat including a hull having a stepped bottom with planing surfaces extending forwardly from generally amidship and a cockpit over said planing surfaces, nad a dirigible outboard motor s'ecuredto the rear end of the boat and adapted to drive the same at planing speeds, said motor including a cowl dirigible with said motor and extending upwardly above the boat hull, said boat further including a pair of spaced upwardly extending, forwardly converging air reaction surfaces symmetrical with respect to the longitudinal centerline of the boat and disposed between the cockpit and motor for stabilizing the boat and directing air rearwardly against the cowl, said dirigible cowl providing reaction surfaces for the air directed rearwardly by the air reaction surfaces on the boat to eflect steering of the boat at planing speeds.

2. In combination, a hydroplaning boat including a hull having a stepped bottom with planing surfaces extending forwardly from generally amidship and a cockpit over said planing surfaces, and a dirigible outboard motor secured to the rear end of the boat and adapted to drive the same at planing speeds, said motor including a cowl dirigible with said motor and extending upwardly above the boat hull, said boat further including an upwardly extending fin disposed longitudinally of the boat and in aligmnent with said motor between the cockpit and motor, said fin providing air reaction surfaces for stabilizing the boat and directing air rearwardly against the cowl, said din'gible cowl providing reaction surfaces for the air directed rearwardly by the fin to effect steering of the boat at planing speeds.

3. The combination set forth in claim 2 wherein the fin comprises longitudinally extending vertical surfaces spaced apart a lesser amount than the width of said cowl, said surfaces including upwardly and forwardly converging portions that meet to form a generally wedgeshaped member.

4. The combination set forth in claim 2 wherein the forward edge of the fin is disposed on the longitudinal 'centerline of the boat and the vertical reaction surfaces extend rearwardly symmetrically and at a constant angle with respect to the centerline.

5. The combination set forth in claim 2 wherein the fin extends vertically generally to the height of the cowl and extends longitudinally from the rear of the cockpit to a location spaced forwardly from the cowl to provide an air slot between the fin and the cowl.

6. In combination, a hydroplaning boat including a hull having a stepped bottom with planing surfaces extending forwardly from generally amidship and a cockpit over said planing surfaces, a dirigible outboard motor secured to the end of the boat and adapted to drive the same at planing speeds, said motor including an engine and a cowl enclosing the engine, said cowl being dirigible with said motor and extending upwardly above the boat hull and having an opening forwardly thereof for admission of combustion air to the engine, an upwardly extending fin disposed longitudinally of the boat and in alignment with said motor between the cockpit and the motor for stabilizing the boat and directing air rearwardly against the cowl, said dirigible cowl providing reaction surfaces for air directed rearwardly by the fin to effect steering of the boat at planing speeds, air scoops projecting from said fin and receiving a portion of said rearwardly directed air, and air conduction means communicating with said air scoops for directing air from the air scoops through the forward cowl opening, said air scoops together with said conduction means providing a carburetor ram whereby some of the air velocity head is converted to a pressure head within the cowl to eliminate negative pressures within the cowl and thereby increase the engine output.

7. In combination, a hydroplaning boat including a hull having a stepped bottom with planing surfaces extending forwardly from generally amidship and a cockpit over said planing surfaces, a dirigible outboard motor secured to the end of the boat and adapted to drive the/same at planing speeds, said motor including an engine and a cowl enclosing the engine, said cowl being dirigible with said motor and extending upwardly above the boat hull and having an opening forwardly thereof for admission of combustion air to the engine, a wedgeshaped fin provided on said boat and extending vertically upwardly generally to the height of the cowl and longitudinally in alignment with said motor from the rear of the cockpit to a location spaced forwardly from the cowl to provide an air slot between the fin and the cowl, said fin serving to stabilize the boat and direct air rearwardly against the cowl, said dirigible cowl providing reaction surfaces for air directed rearwardly by the fin to efifect steering of the boat at planing speeds, air scoops projecting from opposed sides of the fin and opening forwardly to receive a portion of the rearwardly directed air, and a longitudinally extending conduit disposed within the fin and communicating with said air scoops, said conduit having an outlet at the rear end of the fin opposite from the forward cowl opening and directing air from the air scoops across the air slot and into the cowl opening, said air scoops together with said conduit providing a carburetor ram whereby some of the air velocity head is converted to a pressure head within the cowl to eliminate negative pressures within the cowl and thereby increase the engine output.

No references cited. 

